Simple and quick detection of heavy metals in water is essential for numerous applications, particularly due to the increasing global threat of heavy metal contamination of water because of anthropogenic activities including environmental pollution. Some heavy metals are essential nutrients at trace concentration, but all of them pose serious health threats beyond the regulated level. Therefore, the importance of understanding the presence and concentration of heavy metal in water is enormous.
Available heavy metal sensing devices, such as metal selective electrode based devices, enzyme based sensor (bio-sensor), chelating agent based sensors, and the like have unsuitable selectivity and sensitivity. Furthermore, they typically are only useful under laboratory conditions because of their its functional complexities. Traditional sensors equipped with mercury-based electrodes and measuring instruments have short service lifetimes, and they often require pretreatment or modification of samples. Therefore, the process of measurement is slow and not precise. Efforts for toxic heavy metal detection through enzyme based sensors or bio-sensors, as well as other polymeric and chelating agent based sensors, have seen little practical success. In addition, commercially available heavy metal analyzers based on electrochemical techniques requires sample preparation and lack in rapid detection, portability, and sensitivity.
Likewise, advanced heavy metal analyzers including atomic absorption spectrometers and inductively coupled plasma spectrometers are suitable for precise and detailed laboratory level analysis only. Therefore, practical devices suitable for rapid, real-time sensing of different toxic heavy metals dissolved in water for in-field applications, particularly in remote areas or developing nations with a dearth of analytical laboratories, are not presently available. As a result, there is a long-standing unmet demand for operationally simple, rapid and useful heavy metal sensing and detection devices, systems, materials, and methods that are free of the above-noted deficiencies.